1. Field of the Invention
The present invention relates to a radio-tag reading apparatus for reading data from radio tags.
2. Description of the Related Art
A system that uses barcodes, achieving the management of the information about merchandise sold has been established in the physical distribution and retail business. In the system, a barcode is attached to each item of merchandise, each identifying the item of merchandise. To read the barcode, a barcode reader is connected to the point-of-sales (POS) terminal installed in each shop.
The shop clerk uses the barcode reader, reading the barcodes attached to the items of merchandise a customer has bought. The barcode data is input from the barcode reader to the POS terminal. On the basis of the barcode data, the POS terminal processes the sales information about the items of merchandise the customer has bought.
In recent years, radio data carriers called radio tags have come to attract attention in the physical distribution and retail business. The radio tag has an IC chip and an antenna. The IC chip has a memory, which stores ID data, or tag identifier, specific to the radio tag. The radio tag can perform radio communication with a dedicated reader/writer. The reader/writer can therefore read the data stored in the memory and write data to the memory, without contacting the radio tag.
Barcode data cannot be read from barcodes unless the barcode reader scans them one by one. Radio tags communicate with the reader/writer under the control accomplished by a so-called anti-collision method. Thanks to the anti-collision method, the reader/writer can read data from a plurality of radio tags at a time even if the radio tags sparsely exist in the communications region of the reader/writer. Radio tags are therefore advantageous over barcodes in terms of data-processing efficiency.
In the physical distribution and retail business, it is proposed that a system that uses radio tags to achieve the management of the sales information about merchandise should be designed and employed. In the system, a radio tag is attached to each item of merchandise, the radio tag storing the identification code of the item of merchandise. A radio-tag reader/writer is connected to the point-of-sales (POS) terminal installed in each shop.
The shop clerk places the items of merchandise a customer has bought, in the communications region of the radio-tag reader/writer. Then, the radio-tag reader/writer reads all the data items stored in the radio tags attached to the items of merchandise in one go. The data thus read is then input to the POS terminal installed in the shop. On the basis of the data read from the radio tag, the POS terminal processes the sales information about all items of merchandise the customers have bought.
To establish such a system using radio tags, however, the existing POS terminals designed for processing the barcode data must be redesigned in terms of function. Inevitably, the cost of redesigning the POS terminals is so high that the system can hardly be used widely.
Jpn. Pat. Appln. No. 11-96463 discloses a technique of employing both a merchandise management system using barcodes and a merchandise management system using radio tags. The technique involves combining a barcode and a radio tag, forming a merchandise tag, and using such merchandise tags to accomplish merchandise management.
Since barcodes attached to items of merchandise have a fixed format, each barcode contains only a limited amount of information. Therefore, a so-called multi-stage barcode system using multi-stage barcodes, each consisting of two or more barcodes, to manage one item of merchandise, is employed in the apparel industry, in which not only the merchandise ID code, but also other information such as size, color, etc., must be managed about each item of merchandise.
POS terminals for use in the multi-stage barcode system are known (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 7-104901). If such POS terminals adapted to the multi-stage barcode system are used, without being modified, in merchandise management using radio tags, the information items represented by each multi-stage barcode may be stored in two or more radio tags, respectively. As described above, a radio-tag reader/writer can read all the data items stored in the radio tags attached to the items of merchandise in one go. Therefore, the efficiency of reading information will not decrease if a plurality of radio tags are attached to each item of merchandise.
A conventional POS terminal of this type, however, determines that a multi-stage barcode is a wrong one unless its constituent barcodes are input continuously. Assume that the first-stage and second-stage barcodes constituting the multi-stage barcode attached to merchandise A represent data items A1 and A2, respectively, and that the first-stage and second-stage barcodes constituting the multi-stage barcode attached to a merchandise B represent barcode data items B1 and B2, respectively. If barcode data items A1, A2, B1 and B2 are input to the POS terminal in the order they are mentioned, the POS terminal can process the sales information about these two merchandise items A and B. If barcode data item B1 is input after barcode data item A1, or barcode data item A2 is input after barcode data item B1, however, the POS terminal will determine that wrong data has been input.
Thus, in the system where a plurality of radio tags, each storing one barcode, are attached to each item of merchandise, the data items stored in the radio tags attached to merchandise items, respectively, are quickly read in a random order, then input to the POS terminal in the order they were read. Consequently, the POS terminal will probably determine that wrong data has been input.